Ready for a shock?

Monday, January 30, 2006
Translated by Mark Hucko, Checkbiotech

Tobacco plants can now produce vaccine against Lyme disease - a
tick-borne disease from the bacterium Borreliosis. Dr. Heribert
Warzecha, from the University of Wuerzburg, Germany, describes how his
group was able to accomplish this feat in the scientific journal Nature
Biotechnology.


Scientists have already several times tried to generate plant-made
vaccines with the aid of genetic engineering. Generally it works since
many vaccines are protein-based, whose building code can be inserted
into the plant hereditary material as DNA. However, until now, enhanced
plants have produced only minute amounts of the desired substances.

In an innovative approach, Dr. Warzecha and his team built in the
additional hereditary information in the tobacco plant's chloroplasts
- not in the cellular nucleus. Chloroplasts are small cellular
organelles with their own hereditary material, which help the plants to
produce energy from sunlight. The advantage: in one cell there are
around one hundred chloroplasts in comparison to only one nucleus.
Thus, plants with transgenic chloroplasts are more effective vaccine
producers, in that the yield of a target protein is much higher than
those that target the nucleus.

Dr. Wuerzburg's plants produce an OspA protein, which is also found
on the surface of the bacterium Borreliosis. However, OspA alone is not
suitable as a vaccine. To be effective it must be combined with fatty
acids - and to Dr. Wuerzburg's fortunes his genetically modified
plants were able to accomplish this combination.

Experiments with mice showed that the tobacco vaccine has comparable
effectiveness with vaccines produced in conventional bacterial
cultures. However, it appears that people cannot take advantage of this
protection yet, since Borreliosis vaccines have not been granted public
use by regulatory officials.

Nature Biotechnology, Bd. 24, S. 76

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